Bluetooth: Send HCI_Read_Clock_Offset before disconnecting

When the connection is in master role and it is going to be
disconnected based on the disconnection timeout, then send
the HCI_Read_Clock_Offset command in an attempt to update the
clock offset value in the inquiry cache.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/hci.h

@@ -533,6 +533,11 @@ struct hci_cp_read_remote_version {
 	__le16   handle;
 } __packed;
 
+#define HCI_OP_READ_CLOCK_OFFSET	0x041f
+struct hci_cp_read_clock_offset {
+	__le16   handle;
+} __packed;
+
 #define HCI_OP_SETUP_SYNC_CONN		0x0428
 struct hci_cp_setup_sync_conn {
 	__le16   handle;

net/bluetooth/hci_conn.c

@@ -309,6 +309,25 @@ static void hci_conn_timeout(struct work_struct *work)
 			hci_amp_disconn(conn);
 		} else {
 			__u8 reason = hci_proto_disconn_ind(conn);
+
+			/* When we are master of an established connection
+			 * and it enters the disconnect timeout, then go
+			 * ahead and try to read the current clock offset.
+			 *
+			 * Processing of the result is done within the
+			 * event handling and hci_clock_offset_evt function.
+			 */
+			if (conn->type == ACL_LINK &&
+			    test_bit(HCI_CONN_MASTER, &conn->flags)) {
+				struct hci_dev *hdev = conn->hdev;
+				struct hci_cp_read_clock_offset cp;
+
+				cp.handle = cpu_to_le16(conn->handle);
+
+				hci_send_cmd(hdev, HCI_OP_READ_CLOCK_OFFSET,
+					     sizeof(cp), &cp);
+			}
+
 			hci_disconnect(conn, reason);
 		}
 		break;